APOE and early-onset autosomal dominant Alzheimer disease: Indeed, basal levels of these factors, meaning Aβ concentration at picomolar to nanomolar range (Kamenetz et al., 2003; Deshpande et al., 2009; Yankner and Lu, 2009), non-hyperphosphorylated and low nanomolar concentration of tau (Avila et al., 2004; Iqbal et al., 2005; Goedert and Spillantini, 2006) and low ApoE4/ApoE3 ratio (Huang and Mahley, 2014; Mahley and Huang, 2012; Kim et al., 2014) are positive regulators of myelination, while their increased expression or disrupted structure during Alzheimer's Disease progression lead to myelin destabilization and neuronal deficits (Figure 1).